This document provides an overview of basic elements of a C++ program including keywords, tokens, identifiers, data types, variables, constants, operators, expressions, and assignment statements. It discusses standard and user-defined identifiers, standard and user-defined data types like int, float, char, and how to declare and initialize variables. It also covers literals, symbolic constants, arithmetic operators, and type casting.

1. Programming
Fundamentals
Lecture#03
Delivered By:
Hassan iqbal
Superior College Toba Tek Singh

2. Basic Elements of a
C++ Program

3. Keywords:
 The predefined words of the C++ that are
used for special purposes in the source
program.
 Also known as reserved words
 Always written in lowercase
 There are 63 keywords in c++.
Tokens:
 In C++, a source program consists of
keywords, variables(or identifiers), constants,
operators, punctuators.
 These elements of a c++ program are called
tokens.

4. Identifier:
 The unique names used in the program to
represent the variables, constants, functions,
and labels etc. are called identifiers.
 The name of identifier may be 31 characters
long. If the name is more than 31 characters
long , then first 31 characters will be used by
the compiler.
 An identifier may:
 consist of alphabets, digits, and underscore.
 The first character of identifier name must be an
alphabetic letter or underscore.
 The keywords cannot be used as identifier
name.

5. Types of identifiers:
 Standard Identifier
 There are also predefined identifiers in c++
 The predefined identifiers that are used for
special purposes in the source program are
called the standard identifiers.
 E.g cin, cout
 User-defined identifier
 the identifiers defined by the user in the
program are called user-defined identifers.
 E.g variables, user-defined functions, labels

6. Data Types in C++:
 Data types specifies the type of the data
that a variable will hold.
 The data types defines the set of values
and set of operations on those values.
 Two categories:
 Standard Data Types
 The data types that are predefined as a part
of language.
 User defined Data Types
 The data types defined by the user

7.  The “int” data type:
Data Type
Name
Storage
capacity
Range
Int 2 bytes -32768 to 32767
Short int 2 bytes -32768 to 32767
Long int 4 bytes -2147483648 to
2147483647
Signed int Default Default
Unsigned int 2 bytes 0 to 65535
Unsigned long
int
4 bytes 0 to 4294967295

8. Real Type Data:
 The numeric values that have decimal
point in them are called real type data.
 Also known as floating point type data
 The real type data can be represented as
exponential notation i.e in terms of
mantissa and exponent.
 6432157.0 as 6.432157*10^6
 Where 6432157 is mantissa and 6 is the
exponent.
 As 6.432157E6

9. The “float” Data Type
Name Storage Capacity Range
Float 4 bytes 3.14*10−38
to
3.4*1038
Double 8 bytes 1.7*10−308 to
1.7*10308
Long double 10 bytes 3.14*10−4932
to
3.4*104932

10. The “char” data type:
 Used to store a single character such as
“a”, “$” etc.
 When the character is stored into a
variable, the ACII value is stored into the
variable.
 The ASCII value of ‘A’ is 65 and ‘a’ is 97.
 By default the character data type is
unsigned because the ASCII values are
positive.
 The range for unsigned ‘char’ data type is
from 0 to 255.
 For signed ‘char’ its -128 to127

11. Overflow and Underflow:
 An overflow occurs when the value
assigned to a variable is more than the
maximum allowable limit.
 An underflow occurs when the value
assigned to a variable is less then the
minimum allowable limit.

12. Variables:
 A quantity whose value may change
during program execution.
 Used to store program’s input data and
results during program execution.
 There are two basic operations that are
performed onto the variables.
 Declaration
 Initialization

13. Rules for Naming Variables:
 A variable name may consist of:
 Letter, digit, underscore
 The 1st character must be a letter or underscore.
 Special characters except underscore can’t be
used
 The keyword can’t be used as variable name
 Blank spaces are not allowed
 Length may be from 1 to 31 characters
 A variable name declared for one data type
can’t be used for another data type.
 Both uppercase and lowercase letters can be
used
 C++ is a case sensitive language.
 The meaningful name should be given to the
variable.

14. Constants:
 A quantity whose value does not change
during program execution
 Types:
 Literal constants
 Symbolic constants

15. Literal Constants:
 The word ‘literal’ means exact or
accurate.
 A literal is a constant having independent
value that is used in the program source
code.
 E.g 10,10.5, “excellent”
 Types:
 Integer Constant
 Integer constant must lie within the range of
the integer.
 The +ve and –ve signs can also be used.

16.  Floating-Point Constant:
 Letter ‘F’ or ‘L’ is used with the constant to
specify its data type.
 E.g 7.619F, 21.62L
 Character Constant:
 A single character enclosed in single
quotation marks.
 E.g ‘a’, ‘+’
 String Constant:
 A string of characters enclosed in double
quotation marks is known as string constant.
 E.g “abc”, “659329”

17. Symbolic Constants:
 is a constant identifer.
 Once a value is assigned to a symbolic
constant, it can’t be changed during
program execution.
 Can be declared in two ways:
 The ‘const’ keyword
 Using ‘define’ directive

18.  The ‘const’ keyword:
 Used to declare a constant identifier
 E.g const float pi=3.1417;
 The’ define’ directive:
 It’s a preprocessor directive
 Used to define a constant known as
constant macro
 A constant Macro is an identifier, which is
assigned a particular constant value
 Syntax:
 #define identifier expression
 # define pi 3.141593

19. Difference between define
and const
‘define’ directive ‘const’ Qualifier
Used as preprocessor
directive
Used as a statement
Not terminated with the ; Terminated with the ;
Data type of constant
identifier is not specified
Data type is specified

20. Operators and Expressions:
 operators are the special symbols that are
used to perform special operations on the
data.
 Arithmetic operators
 Increment and decrement operator
 Assignment operator
 Relational operator
 Logical operator
 The ‘sizeof’ operator
 Categories of operators:
 unary
 binary

21. Data Type of an Expression
Data types of operands Data type of expression
Int, float, long Float
int., long Long
Int, double, long double Long double

22. o Operators precedence:
o The order in which the arithmetic operators are
evaluated
o Without parenthesis:
o All multiplications and divisions first from left to
right first
o All additions and subtractions are then
performed from left to right
o Operators associativity:
o The order in which the operators of the same
precedence are evaluated
o For example in case of * and / operators, the
operations are performed from left to right

23. Operators Associativity
(), ++postfix, -- postfix Left to right
++ prefix, ++prefix Left to right
*,/,% Left to right
+,- Left to right
=,+=,-=,*=,/= Right to left

24. Assignment Statement
 A statement that is used to assign a value to a
variable.
 E.g c=a+b;
 Rvalue and Lvalue:
 The rvalue is an operand that can be written on
the right side of the assignment operator. It can
be a constant value, variable or na expression
 The lvalue is an operand that can be written on
the left side of the assignment operator.
 It must be a variable.
 Lvalue can be used as Rvalue but Rvalue
cannot be used as Lvalue.

25.  Compound assignment Statement:
 An assignment statement that is used to
assign the same value to many variables
 Also known as multiple assignment
statement
 Compound assignment operator
 Is a combination of arithmetic operator and
the assignment operator

26. Simple assignment
Statement
Assignment Statement using
Compound assignment
operator
X=x+12 X+=12
x=x-4 X-=4
X=x/3 x/=3
Increment and decrement operator:
Postfix, prefix

27. Type Casting
 Explicit type casting
 Cast operator
 (type) expression
int x;
x=(int) 3.156;
cout<<x;
 Implicit type casting
Comments:
 Single line
 Multi line